Probes for STAT3

BACKGROUND: Diffuse large B-cell lymphoma (DLBCL) is the most common form of non-Hodgkin's lymphoma. Signal transducer and activator of transcription 3 (STAT3) is a cytoplasmic transcription with many important functions, including regulation of cell proliferation, differentiation, survival, angiogenesis, and immune response. MATERIALS AND METHODS: In this study, we have compared by means of RNAscope technology STAT3 RNA expression in human DLBCL in a selected group of activated B-cell–like DLBCL (ABC-DLBCL) patients with another group of germinal center B-cell–like DLBCL (GBC-DLBCL) patients. RESULTS: The results have shown that ABC DLBCL tissue samples contained a significantly higher number of STAT3-positive cells as compared with GCB tissue samples. Moreover, by means of confocal immunofluorescence analysis, we have observed that tumor vessels in ABC samples appeared lined by endothelial cells expressing both FVIII and STAT3 signals, while in GCB samples, only few vessels coexpressed FVIII and STAT3. CONCLUSIONS: These data confirm other reports showing that STAT3 is highly expressed and activated in ABC-DLBCL and our previously published data demonstrating that, in primary central nervous system lymphoma, tumor vessels appeared lined by endothelial cells expressing both FVIII and STAT3.

Mantle cell lymphoma (MCL) is an aggressive and rare B-cell non-Hodgkin lymphoma classified in two clinicopathological subtypes according to SOX11 expression and mutation state of immunoglobulin variable region heavy chain (IgVH) gene. The transcription factor SOX11, overexpressed in 78%-93% of MCL patients, plays a central role in modulating tumor microenvironment prosurvival signals and angiogenic genes. In this work, we have explored the lymph node microenvironment of three subgroups of MCL patients classified according to SOX11 expression as negative, light, and strong. CD34+ microvessels, CD4+ and CD8+ T-lymphocytes, CD68+ and CD163+ macrophages, and the oncogene p53 expression were evaluated by immunohistochemistry. Moreover, STAT3 mRNA expression was analyzed by RNA-scope assay. Our results confirmed increased angiogenesis in the sample of patients positive to SOX11 compared to the negative ones and demonstrated that angiogenesis and SOX11 expression positively correlate to a higher T-lymphocytes inflammatory infiltrate. On the contrary, angiogenesis and SOX11 expression negatively correlate with macrophage's inflammatory infiltrate and p53 expression. STAT3 mRNA expression level was not relevant concerning angiogenesis or SOX11 expression. Overall, our data indicate that, in MCL, SOX11 expression is associated with increased angiogenesis and a high CD4+ and CD8+ T-cell infiltration, which are not sustained by CD163+ macrophages infiltrate and p53 expression

Diffuse large B‑cell lymphoma (DLBCL) is a highly heterogeneous malignant tumor type, and epigenetic modifications such as acetylation or deacetylation serve vital roles in its development. Chidamide, a novel histone deacetylase inhibitor, exerts an anticancer effect against various types of cancer. The present study aimed to evaluate the cellular effect of chidamide on a number of DLBCL cell lines and to investigate its underlying mechanism. The results demonstrated that chidamide induced the death of these cells in a concentration‑(0‑30 µmol/l) and time‑dependent (24‑72 h) manner, as determined using the Cell Counting Kit‑8 cell viability assay. Moreover, chidamide promoted cellular apoptosis, which was identified via flow cytometry and western blot analysis, with an increase in cleaved caspase‑3 expression and a decrease in Bcl‑2 expression. Chidamide treatment also decreased the expression level of STAT3 and its phosphorylation, which was accompanied by the downregulation of a class‑I histone deacetylase (HDAC) inhibitor, chidamide. Collectively, these data suggested that chidamide can be a potent therapeutic agent to treat DLBCL by inducing the apoptotic death of DLBCL cells by inhibiting the HDACs/STAT3/Bcl‑2 pathway.

Aryl hydrocarbon receptor (AhR) activation promotes intestinal barrier repair and enhances the gut mucosal barrier function in inflammatory bowel diseases (IBD). Spermidine is beneficial in several murine models of IBD and may affect AhR activity. However, the precise effects of spermidine on the intestinal barrier and AhR remain unclear. This study was designed to investigate whether spermidine affects AhR and gut barrier function in IBD models as well as, its underlying mechanism.We used dextran sulfate sodium (DSS)- and 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced mice, as well as, Caco2 cells incubated with TNF-α and IFN-γ to establish multiple IBD models, followed by spermidine intervention. Alcian blue/Periodic acid-Schiff (AB/PAS) staining, Fluorescein isothiocyanate (FITC)-dextran permeability assay, transepithelial electrical resistance (TER), tight junction protein (TJs) expression, and 16S rRNA scope in situ hybridization were performed to assess intestinal barrier function. AhR expression and the associated pathways were measured. AhR-targeted adeno-associated virus (AAV) and siRNA were used to explore the related molecular mechanisms.Spermidine significantly attenuated the increased intestinal permeability, decreased TER, abnormal distribution of TJs in colitis, and bacterial translocation from the gut tract. Additionally, it significantly increased AhR and Nrf2 expression and inhibited STAT3 phosphorylation. However, the protective effects of spermidine and the related alterations in pathway proteins were largely abolished by the specific inhibition of AhR.Our study demonstrated that spermidine rescues intestinal barrier defects in mice with colitis via the AhR-Nrf2 and AhR-STAT3 pathways, providing a potential therapeutic agent for IBD and other conditions associated with dysregulated gut barrier function.